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Re: Thread starvation with mutex



Perez-Gonzalez, Inaky wrote:
> > I admit I don't know much about the RTNPTL implementation, but having
> > thought about scheduling issues due to the other recent threads on
> > phil-list, I see that real-time futex wakeups would _not_ guarantee
> > that a SCHED_FIFO task would ever acquire a mutex which SCHED_OTHER
> > tasks were periodically releasing.  (Think about multiple CPUs).
> 
> If you have strict ownership transferal _and_ priority sorted wake ups
> in the kernel, then that problem should not be an issue at all,

Yes, if you have both those things.

I was thinking of an old RT futex patch which simply offered priority
sorted wakeups, and was not sure if that's what this thread's question
about "RTNTPL offering complete RT support" referred to.

The down side is that if you always have strict ownership transferral,
you get very poor performance in a large class of algorithms which
take and release locks regularly - such as producer-consumer queuing
to pick a classic one.

-- Jamie




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